Apparatus for measuring temperature

ABSTRACT

The disclosure relates to an apparatus for measuring temperature, comprising a temperature-sensitive sensor (1, 1&#39;), whose electric properties, for example, resistance, vary with the temperature, for example, one thermistor (2, 2&#39;, 3 or 3&#39;) which is connected to electric lines (5, 6) which, in turn, may be connected to a read-off unit for reading off the values of current, voltage or the like corresponding to the temperature. In the apparatus according to the invention, the electric lines are disposed between two insulating layers (7, 8) which present mutually offset holes (9, 10) each in register with their respective line (5, 6), whereby these may easily be connected to different sensing terminals in the above-mentioned read-off units. The apparatus according to the invention is primarily intended to be used for medicinal temperature measurement, but may, naturally, also be used in other contexts, for example, in pure industrial application where a simple and economical but nevertheless reliable reading-off of temperature is desired.

TECHNICAL FIELD

The present invention relates to an apparatus for measuring temperature,comprising a temperature-sensitive sensor, whose electric properties,for example, resistance, vary with the temperature, for example, athermistor which is connected to electric lines which, in turn, may beconnected to a read-off unit for reading off the values of current,voltage or the like corresponding to the temperature.

The apparatus according to the invention is primarily intended to beused for medicinal temperature measurement. Consequently, one aspect ofthe invention is to make the apparatus so simple and cheap that it maybe disposed of after use, that is to say that it may not be reused.

At the same time however, it should be possible to manufacture theapparatus with such precision that the reader can rely with greatcertainty on the read-off values, this being, clearly, of the greatestimportance precisely in medical use.

However, it is clear to a person skilled in the art that the apparatusaccording to the invention may be used in other contexts, for example,in pure industrial application in which a simple and inexpensive butnevertheless reliable reading-off of temperature is desired.

BACKGROUND ART

Swedish patent application No. 78.03046-7 (U.S. Ser. No. 779 152 filedMar. 18, 1977, which is the parent of U.S. patent application Ser. No.41,551, filed May 23, 1979, now U.S. Pat. No. 4,317,367) and the twocopending PCT Applications PCT/SE78/00012 (U.S. patent application Ser.No. 131,079, filed July 3, 1978, now U.S. Pat. No. 4,269,633) andPCT/SE78/00013 (U.S. patent application Ser. No. 131,078, filed June 1,1979, now U.S. Pat. No. 4,253,334) describe different embodiments of anapparatus similar to that according to the invention and how theapparatus according to the invention may be used. The concept formingthe basis of the present invention is, in this instance, to realize suchan apparatus, but of simpler type and adapted to a simpler manner ofmanufature.

In U.S. patent applications Ser. No. 787,422, filed Apr. 14, 1977, nowU.S. Pat. No. 4,200,970 and Ser. No. 879,193, filed Feb. 21, 1978) thereare described different trimming processes for apparatuses similar tothat according to the invention. Such trimming processes could well beused for trimming the apparatus according to the invention. Preferablyhowever, use is made instead of an assortment of the type described inco-filed application PCT/SE78/00012 (U.S. patent application Ser. No.131,079, filed July 3, 1978, now U.S. Pat. No. 4,296,633).

DESCRIPTION OF THE INVENTION

The apparatus according to the invention is characterized in that theabove-mentioned electric lines are disposed between two insulated layerswhich display mutually offset holes in register with each respectiveline, whereby these may easily be connected to different sensingterminals in the above-mentioned read-off unit.

The above-mentioned construction permits of a very simple manner ofmanufacture which will be described in greater detail below under thetitle "Preferred manner of manufacture".

Preferably, the two insulated layers consist of plastics-coated paperwhich may easily be thermally sealed to mutually contact each other and,respectively, to contact with other materials.

In order to increase the possibilities of rapid read-off, the twoinsulating layers present holes suitably located in register with eachother and in register with the sensor. In order, in such an event, toprevent short-circuiting when the apparatus is used in wet or humidatmosphere, for example, in the mouth of a patient, the sensor and thehole in register therewith are covered by two insulating outer layerswhich do not, however, cover the mutually offset holes.

The sensor which is used may consist of two thermistors which are eachconnected by their first terminal to an intermediate line and are eachconnected by their second terminal to the above-mentioned electric line.As a result, the thermistors which are used need not be trimmed.Instead, it is possible, by selection, to choose two thermistors which,in the correct coupling, give the desired value of the electric propertywhich is used for measuring the temperatures.

At the same time, handling of the thermistors (which normally are verysmall) is facilitated. The above-mentioned intermediate line may, forexample, consist of a short strip of copper foil or other similarelectrically-conductive material. Two such thermistors fixedly retainedon one such copper foil are, in this case, easier to handle thanseparate thermistors.

The apparatus according to the invention is suitably designed inelongate form. The two electric lines may, in this case, be ofsubstantially the same length as the two elongate insulating layersbetween which they are located. In such an event, the sensor is placedclose to one end, whereas the mutually offset holes are placed proximalto the opposite end of the insulating layer. This arrangement makes itpossible that the non-insulated lines may be grasped by theabove-mentioned read-off unit, while the sensor is still located in themouth of a patient.

As read-off unit, use may be made, for example, of one of thosedescribed in copending PCT application PCT/SE78/00013 (U.S. patentapplication Ser. No. 131,078, filed June 1, 1979, now U.S. Pat. No.4,253,334), whose contents are herewith incorporated in the presentapplication.

The insulating outer layers may also, suitably, be of plastics-coatedpaper or other liquid-tight flexible material. They can, in thiscontext, extend out over one end of the two elongate insulating layersso that they also insulate the ends of the lines located therebetween.This end of the apparatus, that is to say that at which the sensor islocated, may be rounded-off without exposing the electric lines. If, atthe same time, the materials for the above-mentioned lines, insulatinglayers and outer layers are selected such that high flexibility isimparted to the apparatus in its entirety, the apparatus will beparticularly suited for temperature measurement in, for example, themouth where such properties are required.

By using plastics-coated paper for both the inner, insulating layers andthe outer, insulating layers, the two inner layers may be mutuallycombined, both between and outside the electric lines disposed inparallel, at the same time as the insulating outer layers may becombined, on the one hand mutually and on the other hand with the twoinner, insulating layers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a preferred embodiment of the apparatus according to theinvention, certain parts of the different material layers having beenremoved.

FIG. 2 is a side elevation of the same apparatus.

FIG. 3 is an enlargement of the forward end of the apparatus.

FIG. 4 shows an alternative embodiment of the sensor which is used inthe apparatus according to FIGS. 1-3.

FIG. 5 is intended to illustrate a simple method for realizing theapparatus shown in FIGS. 1-3.

FIG. 6 shows, finally, one of the material layers used in therealization according to FIG. 5.

PREFERRED EMBODIMENT OF THE INVENTION

The apparatus shown as an example comprises, thus, atemperature-sensitive sensor which is designated in its entirety with 1in FIGS. 1 and 3, and 1', respectively, in FIG. 4. This sensor consists,according to FIGS. 1-3 of two thermistors 2 and 3 which areinterconnected via an intermediate line 4. In FIG. 4, the thermistorsare, instead, designated 2' and 3', respectively, whereas theintermediate line consists of a copper foil which is designated 4'. Theterminals of the one thermistor are, here, designated 2a' and 2b',whereas the terminals of the second thermistor are designated 3a' and3b'.

Furthermore, the two thermistors 2 and 3 are connected to electric lines5 and 6, respectively. In the embodiment according to FIG. 4, thecorresponding line is connected to the terminals 2a' and 3a'.

The two electric lines 5 and 6 are encapsulated between two inner,insulating layers 7 and 8 which present mutually offset holes 9, 10,respectively, each in register with their respective lines 6, 5,respectively. As a result, these two lines 6 and 5 are exposed throughthe holes 9 and 10. More particularly, the opening 9 extends through theinsulating layer 7 to expose the conductor 6 for the purpose ofpermitting electrical contact therewith from one side of the apparatus,while the opening 10 extends through the insulating layer 8 to exposethe conductor 5 for the purpose of permitting electrical contacttherewith from an opposite side of the apparatus. Because the openings9, 10 are offset, the conductors 5, 6 can be engaged from opposite sidesof the apparatus by a temperature reading unit (not shown) adapted toreceive from the conductors 5, 6 electrical signals representing atemperature sensed by the sensor 1 and to convert the signals into areadable temperature value. The temperature reading unit can be similarto the one disclosed in U.S. Pat. No. 4,253,334, whose contents havealready been incorporated herein by reference thereto.

The two insulating layers 7 and 8 consist suitably of plastics-coatedpaper, which facilitate manufacture, since the thermal sealing may beused to unite the two layers with each other and with other materials.At the same time, use of the apparatus according to the invention ismade possible in a humid environment.

The two insulating layers 7 and 8 present, furthermore, holes 11 locatedin register with each other and with the sensor.

The sensor 1 and the holes 11 located in register therewith are coveredby two insulating, outer layers 12 and 13. These outer layers areprovided only along the forward end of the apparatus and, thus, do notcover the holes 9 and 10.

As is most clearly apparent from FIG. 1, the two electric lines 5 and 6are substantially of the same length as the two elongate, insulatinglayers 7 and 8, between which they are located, the sensor 1 beinglocated proximal to one end which, as above and in the followingdiscussion, will be designated as the forward end of the apparatus,whereas the mutually offset holes 9 and 10 are located proximal to theopposite end of the insulating layers.

The two insulating, outer layers 12 and 13 extend out over the forwardend of the two inner, insulating layers, such that they also insulatethe ends of the lines 5 and 6 located therebetween. As a result, thisforward end may be rounded-off without exposing the lines.

PREFERRED MANNER OF MANUFACTURE

The apparatus according to the invention is suitably manufactured in themanner which is illustrated in greater detail by FIGS. 5 and 6. Aconducting means 14, for example a thin copper wire, is led in zig-zagformation between two paper webs 7c and 8c. The webs 7c, 8c includepunched holes 15, 17 and 16, 18, respectively, and are synchronouslydriven by members entering these holes, such as driving sprockets, pins,etc., mounted on a drum (not shown) or the like. In the preferredembodiment, the pins entering holes 17 and 18 are larger than the pinsentering holes 15 and 16 so as to control the spacing between lines 5and 6. That is, the smaller pins produce a reduced space between lines 5and 6 for each unit to be formed, whereas the larger pins produce alarger space between the lines 5 and 6 of one unit and an adjacent unit.Also, in the preferred embodiment, the paper webs 7c, 8c are heat sealedtogether and thereby maintain the lines 5 and 6 in position between thepaper webs. In addition, the web 7c includes a hole 9 formed therein,and the web 8c includes a hole 10 formed therein, and as a result of thesynchronous driving of the webs, holes 9 and 10 are mutually offset fromeach other so that hole 9 is in register with line 5, and hole 10 is inregister with line 6. Both of the webs are provided with holes 11 which,as a result of the synchronous advancement, will be located in registerwith each other. In register with these holes 11, the lines 5 and 6formed by the wire 14 will also be exposed, to which lines the sensor 1is connected by soldering or the like. Thereafter, the two outer stripportions of the webs 7c and 8c with the holes 15, 16, 17 and 18 may becut off. This is intimated at the arrow 19. Thereafter, the outer layers12 and 13 are applied, which also suitably is effected in the form oftwo webs. For the sake of simplicity however, no such complete webs areshown in FIG. 5. Finally, the forward end of the apparatus isrounded-off by punching, this suitably being effected in conjunctionwith the punching-out in its entirety of the apparatus from the producedmaterial web.

FIG. 5 illustrates the manner of manufacture, naturally schematically,in a highly concentrated state. In practice, the various manufacturingoperations are effected by means of different devices in completelyseparate processes, for example, in separate stations along a materialweb of greater length, this being constructed gradually.

Finally, FIG. 6 shows a material web which may constitute one of thematerial webs 7c and 8c, which differ from each other only through thelocation of the holes 9 and 10, respectively. The holes 17 and 18, and15 and 16, respectively are, thus, identical, at the same time as bothwebs contain holes 11.

Naturally, the invention is not restricted only to the above-describedembodiment, but may be varied within the spirit and scope of theappended claims. For example, the plastics-coated paper layers 7 and 8may be replaced by layers of waxed paper with, for example, a hotmeltcoating on one side for the purposes of unification. Alternatively, theymay be replaced by normal paper without moisture insulation, since thismay be provided by means of the outer layers 12 and 13. The sealing may,in this case, be realized with the assistance of hotmelt, adhesive orother suitable binder.

We claim:
 1. Apparatus for measuring temperature, comprising a firstelectrical insulating layer, having a first surface and a second surfaceopposite said first surface of said first insulating layer; a secondelectrical insulating layer, having a first surface and a second surfaceopposite said first surface of said second insulating layer, said secondsurface of said second insulating layer being attached to said surfaceof said first insulating layer; first and second electrical conductorsdisposed between said first and second insulating layers; sensing meanslocated within at least one of said first and second insulating layersfor sensing temperature, said sensing means being electrically connectedto said first and second electrical conductors and having electricalproperties which vary with temperature; a first opening formed in saidfirst surface of said first insulating layer and extending through saidfirst insulating layer to said second surface thereof so as to exposesaid first electrical conductor for the purpose of permitting electricalcontact therewith from one side of said apparatus; and a second openingformed in said first surface of said second insulating layer andextending through said second insulating layer to said second surfacethereof so as to expose said second electrical conductor for the purposeof permitting electrical contact therewith from the other side of saidapparatus, said first opening being offset from said second opening suchthat said first electrical conductor is insulated by said secondinsulating layer to thereby inhibit electrical contact with said firstelectrical conductor from said other side of said apparatus and saidsecond electrical conductor is insulated by said first insulating layerto thereby inhibit electrical contact with said second electricalconductor from said one side of said apparatus, whereby said first andsecond electrical conductors can be contacted electrically from oppositesides of said apparatus by a temperature reading unit adapted to receivefrom said first and second electrical conductors electrical signalsrepresenting a temperature sensed by said sensing means and then convertthe signals into a readable temperature value.
 2. The apparatus of claim1, wherein said openings are laterally offset from each other.
 3. Theapparatus of claim 1, wherein said first and second insulating layersare plastic-coated paper.
 4. The apparatus of claim 1, wherein saidsensing means includes a pair of thermistors.
 5. The apparatus of claim1, wherein said apparatus is highly flexible.
 6. The apparatus of claim1, further comprising receiving means for receiving said sensing means,said receiving means including a first hole provided in said firstinsulating layer and a second hole provided in said second insulatinglayer, said second hole being in register with said first hole.
 7. Theapparatus of claim 6, further comprising a third insulating layerapplied to said first surface of said first insulating layer so as tocover said first hole and said sensing means without covering said firstopening in said first insulating layer and a fourth insulating layerapplied to said first surface of said second insulating layer so as tocover said second hole and said sensing means without covering saidsecond opening in said first insulating layer.
 8. The apparatus of claim7, wherein said first and second electrical conductors are parallel toeach other.
 9. The apparatus of claim 8, wherein said first and secondinsulating layers are mutually united between said first and secondelectrical conductors and laterally outwardly of said first and secondelectrical conductors and said third and fourth insulating layers areunited to each other and to said first and second insulating layers,respectively.
 10. The apparatus of claim 7, wherein said first andsecond electrical conductors are substantially the same length as saidfirst and second insulating layers.
 11. The apparatus of claim 10,wherein said sensing means is located proximal to one end of saidapparatus and said first and second openings are located proximal to anopposite end of said apparatus.
 12. The apparatus of claim 11, whereinsaid one end of said apparatus is rounded-off.
 13. The apparatus ofclaim 11, wherein said third and fourth insulating layers protrudeoutwardly beyond said first and second insulating layers at said one endof said apparatus, the protruding portions of said third and fourthinsulating layers being adhered to each other so as to electricallyinsulate adjacent ends of said first and second electrical conductors.14. The apparatus of claim 13, wherein said third and fourth insulatinglayers are made from plastic-coated paper.
 15. The apparatus of claim13, wherein said third and fourth insulating layers are made from aliquid-tight flexible material.